[Kenwood] TR-7730 TX off freq.

[fredv]

Thanks to all for your help. I should be able
to get the rig on freq. now. Of course I may have
to go borrow a counter until I get around to fixing the
7904A. But maybe its time to get something
newer? It does take up a lot of space. Perhaps it was all my stuff on
top of the scope
and the heat killed it. And here I'm the one telling all
the other guys not to put stuff on top of the power
supplies and overheat them!

73,
Fred
N1DEC

----- Original Message -----
From: <ma.locksmith@juno.com>
To: <fredvp@snet.net>
Sent: Friday, August 09, 2002 8:39 PM
Subject: Re: [Kenwood] TR-7730 TX off freq.


>
> On Fri, 9 Aug 2002 19:30:39 -0400 "fredv" <fredvp@snet.net> writes:
> > Hi Ed
> >
> > Well, what was supposed to be a fun job fixing this rig today has
> > been temporarily put on hold as my trusty Tek 7904A scope
> > died today. It just happens to also be my freq counter (a plug-
> > in). Now I have to fix that.
> >
> > But anyway, I looked at the circuit and I see only two
> > crystals with trimmers. A 42.6mhz Rx and a 46.1666mhz Tx in the
> > PLL section.
>
> ***********  Interesting.....  three times the first is 127.8 and
three
> times the second is 138.5.  Subtract and you get the IF of 10.7.  That
> means I'd start looking at the 46.1666 oscillator.  If you are off by
5
> kHz low at transmit frequency, you would be 1600-1700 Hz low at the
> fundamental.  You should be able to get that within 25 Hz.
>
>
> There is also a 10.24Mhz crystal in another section of
> > the PLL,
> ********** I'd expect this to be the reference oscillator for the PLL
>
> and a 10.245Mhz crystal in the rx/tx unit.
>
> ***************and this is the second conversion LO.  The first IF is
> 10.7.  If you subtract 10.245 from 10.7, you get 455 kHz which is a
> normal 2nd IF and detector frequency.
>
> Ed
>
>
> I has just
> > finished
> > checking the 10.245 one when the scope went out. It was ok.
> > I put a copy of the block diagram up at
> > http://www.qsl.net/n1dec/files/7730blk.JPG if
> > you care to see.
> > Thanks for your help. By the way, the Azden rig you helped me with
> > once still works great!
> >
> > Fred
> > N1DEC
> >
>
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